ARM: cpuidle: add const qualifier to cpuidle_ops member in structures

The core code does not modify smp_operations structures. To clarify it,
this patch adds 'const' qualifier to the 'ops' member of struct
of_cpuidle_method.

This change allows each arm cpuidle code to add 'const' qualifier to
its cpuidle_ops structure.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

arch/arm/include/asm/cpuidle.h

@@ -36,7 +36,7 @@ struct cpuidle_ops {
 
 struct of_cpuidle_method {
 	const char *method;
-	struct cpuidle_ops *ops;
+	const struct cpuidle_ops *ops;
 };
 
 #define CPUIDLE_METHOD_OF_DECLARE(name, _method, _ops)			\